Return-Path: Received: from mail-iw0-f174.google.com ([209.85.214.174]:41162 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750724Ab0LQS5v convert rfc822-to-8bit (ORCPT ); Fri, 17 Dec 2010 13:57:51 -0500 Received: by iwn9 with SMTP id 9so1021514iwn.19 for ; Fri, 17 Dec 2010 10:57:50 -0800 (PST) In-Reply-To: References: <1292610010-19084-1-git-send-email-andros@netapp.com> <1292610010-19084-2-git-send-email-andros@netapp.com> <20101217184047.GD11515@fieldses.org> Date: Fri, 17 Dec 2010 13:57:50 -0500 Message-ID: Subject: Re: [PATCH_V4 1/9] SUNRPC new transport for the NFSv4.1 shared back channel From: "William A. (Andy) Adamson" To: "J. Bruce Fields" Cc: trond.myklebust@netapp.com, bfields@redhat.com, linux-nfs@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Fri, Dec 17, 2010 at 1:54 PM, William A. (Andy) Adamson wrote: > On Fri, Dec 17, 2010 at 1:40 PM, J. Bruce Fields wrote: >> On Fri, Dec 17, 2010 at 01:20:02PM -0500, andros@netapp.com wrote: >>> From: Andy Adamson >>> >>> Create a new transport for the shared back channel.l Move the current sock >>> create and destroy routines into the new transport ops. >>> >>> Reference the back channel transport across message processing (recv/send). >>> >>> Signed-off-by: Andy Adamson >>> --- >>> ?include/linux/sunrpc/svcsock.h | ? ?1 + >>> ?net/sunrpc/svc.c ? ? ? ? ? ? ? | ? 18 +++--- >>> ?net/sunrpc/svcsock.c ? ? ? ? ? | ?122 +++++++++++++++++++++++++++++++++------- >>> ?3 files changed, 112 insertions(+), 29 deletions(-) >>> >>> diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h >>> index 1b353a7..3a45a80 100644 >>> --- a/include/linux/sunrpc/svcsock.h >>> +++ b/include/linux/sunrpc/svcsock.h >>> @@ -45,6 +45,7 @@ int ? ? ? ? svc_sock_names(struct svc_serv *serv, char *buf, >>> ?int ? ? ? ? ?svc_addsock(struct svc_serv *serv, const int fd, >>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? char *name_return, const size_t len); >>> ?void ? ? ? ? svc_init_xprt_sock(void); >>> +void ? ? ? ? svc_init_bc_xprt_sock(void); >>> ?void ? ? ? ? svc_cleanup_xprt_sock(void); >>> ?struct svc_xprt *svc_sock_create(struct svc_serv *serv, int prot); >>> ?void ? ? ? ? svc_sock_destroy(struct svc_xprt *); >>> diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c >>> index 6359c42..3520cb3 100644 >>> --- a/net/sunrpc/svc.c >>> +++ b/net/sunrpc/svc.c >>> @@ -488,10 +488,6 @@ svc_destroy(struct svc_serv *serv) >>> ? ? ? if (svc_serv_is_pooled(serv)) >>> ? ? ? ? ? ? ? svc_pool_map_put(); >>> >>> -#if defined(CONFIG_NFS_V4_1) >>> - ? ? svc_sock_destroy(serv->bc_xprt); >>> -#endif /* CONFIG_NFS_V4_1 */ >>> - >>> ? ? ? svc_unregister(serv); >>> ? ? ? kfree(serv->sv_pools); >>> ? ? ? kfree(serv); >>> @@ -1264,7 +1260,7 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req, >>> ?{ >>> ? ? ? struct kvec ? ? *argv = &rqstp->rq_arg.head[0]; >>> ? ? ? struct kvec ? ? *resv = &rqstp->rq_res.head[0]; >>> - ? ? int ? ? ? ? ? ? error; >>> + ? ? int ? ? ? ? ? ? ret; >>> >>> ? ? ? /* Build the svc_rqst used by the common processing routine */ >>> ? ? ? rqstp->rq_xprt = serv->bc_xprt; >>> @@ -1292,12 +1288,16 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req, >>> ? ? ? svc_getu32(argv); ? ? ? /* XID */ >>> ? ? ? svc_getnl(argv); ? ? ? ?/* CALLDIR */ >>> >>> - ? ? error = svc_process_common(rqstp, argv, resv); >>> - ? ? if (error <= 0) >>> - ? ? ? ? ? ? return error; >>> + ? ? /* Hold a reference to the back channel socket across the call */ >>> + ? ? svc_xprt_get(serv->bc_xprt); >> >> Either we already have a reference, in which case this is unnecessary, >> or we don't, in which case this is risky. > > This is done so that when svc_xprt_put is called due to an svc_drop > (svc_xprt_release, svc_xprt_put) it is not freed. ?It's not risky > because AFAICS it's the way the rpc server code is intended to work. > Note that svc_recv calls svc_xprt_get, and svc_send calls svc_xprt_put > for the same reason. I take it back - as written, it might be risky :) Perhaps I should make sure that the xpt_ref = 1 before returning from bc_svc_process. -->Andy > >> The nfs client code knows when it wants to create and destroy the >> backchannel, so I think all you want is to create the svc_xprt when you >> create the backchannel and then put it once when you bring it down. > > Correct, and without the references in bc_svc_process, svc_drop == freeing. > > -->Andy >> >> --b. >> >>> + ? ? ret = svc_process_common(rqstp, argv, resv); >>> + ? ? if (ret <= 0) >>> + ? ? ? ? ? ? return ret; >>> >>> ? ? ? memcpy(&req->rq_snd_buf, &rqstp->rq_res, sizeof(req->rq_snd_buf)); >>> - ? ? return bc_send(req); >>> + ? ? ret = bc_send(req); >>> + ? ? svc_xprt_put(serv->bc_xprt); >>> + ? ? return ret; >>> ?} >>> ?EXPORT_SYMBOL(bc_svc_process); >>> ?#endif /* CONFIG_NFS_V4_1 */ >>> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c >>> index 07919e1..5875551 100644 >>> --- a/net/sunrpc/svcsock.c >>> +++ b/net/sunrpc/svcsock.c >>> @@ -66,6 +66,13 @@ static void ? ? ? ? ? ? ? ?svc_sock_free(struct svc_xprt *); >>> ?static struct svc_xprt *svc_create_socket(struct svc_serv *, int, >>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? struct net *, struct sockaddr *, >>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? int, int); >>> +#if defined(CONFIG_NFS_V4_1) >>> +static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net *, struct sockaddr *, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int, int); >>> +static void svc_bc_sock_free(struct svc_xprt *xprt); >>> +#endif /* CONFIG_NFS_V4_1 */ >>> + >>> ?#ifdef CONFIG_DEBUG_LOCK_ALLOC >>> ?static struct lock_class_key svc_key[2]; >>> ?static struct lock_class_key svc_slock_key[2]; >>> @@ -1184,6 +1191,79 @@ static struct svc_xprt *svc_tcp_create(struct svc_serv *serv, >>> ? ? ? return svc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags); >>> ?} >>> >>> +#if defined(CONFIG_NFS_V4_1) >>> +static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net *, struct sockaddr *, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int, int); >>> +static void svc_bc_sock_free(struct svc_xprt *xprt); >>> + >>> +static struct svc_xprt *svc_bc_tcp_create(struct svc_serv *serv, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net *net, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct sockaddr *sa, int salen, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int flags) >>> +{ >>> + ? ? return svc_bc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags); >>> +} >>> + >>> +static void svc_bc_tcp_sock_detach(struct svc_xprt *xprt) >>> +{ >>> +} >>> + >>> +/* These bc ops are never called. The shared fore channel is used instead */ >>> +static int svc_bc_tcp_recvfrom(struct svc_rqst *rqstp) >>> +{ >>> + ? ? return 0; >>> +} >>> + >>> +static int svc_bc_tcp_sendto(struct svc_rqst *rqstp) >>> +{ >>> + ? ? return 0; >>> +} >>> + >>> +static void svc_bc_tcp_prep_reply_hdr(struct svc_rqst *rqstp) >>> +{ >>> +} >>> + >>> +static void svc_bc_release_skb(struct svc_rqst *rqstp) >>> +{ >>> +} >>> + >>> +static int svc_bc_tcp_has_wspace(struct svc_xprt *xprt) >>> +{ >>> + ? ? return 0; >>> +} >>> + >>> +static struct svc_xprt *svc_bc_tcp_accept(struct svc_xprt *xprt) >>> +{ >>> + ? ? return NULL; >>> +} >>> + >>> +static struct svc_xprt_ops svc_tcp_bc_ops = { >>> + ? ? .xpo_create = svc_bc_tcp_create, >>> + ? ? .xpo_recvfrom = svc_bc_tcp_recvfrom, >>> + ? ? .xpo_sendto = svc_bc_tcp_sendto, >>> + ? ? .xpo_release_rqst = svc_bc_release_skb, >>> + ? ? .xpo_detach = svc_bc_tcp_sock_detach, >>> + ? ? .xpo_free = svc_bc_sock_free, >>> + ? ? .xpo_prep_reply_hdr = svc_bc_tcp_prep_reply_hdr, >>> + ? ? .xpo_has_wspace = svc_bc_tcp_has_wspace, >>> + ? ? .xpo_accept = svc_bc_tcp_accept, >>> +}; >>> + >>> +static struct svc_xprt_class svc_tcp_bc_class = { >>> + ? ? .xcl_name = "tcp-bc", >>> + ? ? .xcl_owner = THIS_MODULE, >>> + ? ? .xcl_ops = &svc_tcp_bc_ops, >>> + ? ? .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP, >>> +}; >>> + >>> +void svc_init_bc_xprt_sock(void) >>> +{ >>> + ? ? svc_reg_xprt_class(&svc_tcp_bc_class); >>> +} >>> +EXPORT_SYMBOL_GPL(svc_init_bc_xprt_sock); >>> +#endif /* CONFIG_NFS_V4_1 */ >>> + >>> ?static struct svc_xprt_ops svc_tcp_ops = { >>> ? ? ? .xpo_create = svc_tcp_create, >>> ? ? ? .xpo_recvfrom = svc_tcp_recvfrom, >>> @@ -1509,41 +1589,43 @@ static void svc_sock_free(struct svc_xprt *xprt) >>> ? ? ? kfree(svsk); >>> ?} >>> >>> +#if defined(CONFIG_NFS_V4_1) >>> ?/* >>> - * Create a svc_xprt. >>> - * >>> - * For internal use only (e.g. nfsv4.1 backchannel). >>> - * Callers should typically use the xpo_create() method. >>> + * Create a back channel svc_xprt which shares the fore channel socket. >>> ? */ >>> -struct svc_xprt *svc_sock_create(struct svc_serv *serv, int prot) >>> +static struct svc_xprt *svc_bc_create_socket(struct svc_serv *serv, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int protocol, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net *net, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct sockaddr *sin, int len, >>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int flags) >>> ?{ >>> ? ? ? struct svc_sock *svsk; >>> - ? ? struct svc_xprt *xprt = NULL; >>> + ? ? struct svc_xprt *xprt; >>> + >>> + ? ? if (protocol != IPPROTO_TCP) { >>> + ? ? ? ? ? ? printk(KERN_WARNING "svc: only and TCP sockets" >>> + ? ? ? ? ? ? ? ? ? ? " supported on shared back channel\n"); >>> + ? ? ? ? ? ? return ERR_PTR(-EINVAL); >>> + ? ? } >>> >>> - ? ? dprintk("svc: %s\n", __func__); >>> ? ? ? svsk = kzalloc(sizeof(*svsk), GFP_KERNEL); >>> ? ? ? if (!svsk) >>> - ? ? ? ? ? ? goto out; >>> + ? ? ? ? ? ? return ERR_PTR(-ENOMEM); >>> >>> ? ? ? xprt = &svsk->sk_xprt; >>> - ? ? if (prot == IPPROTO_TCP) >>> - ? ? ? ? ? ? svc_xprt_init(&svc_tcp_class, xprt, serv); >>> - ? ? else if (prot == IPPROTO_UDP) >>> - ? ? ? ? ? ? svc_xprt_init(&svc_udp_class, xprt, serv); >>> - ? ? else >>> - ? ? ? ? ? ? BUG(); >>> -out: >>> - ? ? dprintk("svc: %s return %p\n", __func__, xprt); >>> + ? ? svc_xprt_init(&svc_tcp_bc_class, xprt, serv); >>> + >>> + ? ? serv->bc_xprt = xprt; >>> + >>> ? ? ? return xprt; >>> ?} >>> -EXPORT_SYMBOL_GPL(svc_sock_create); >>> >>> ?/* >>> - * Destroy a svc_sock. >>> + * Free a back channel svc_sock. >>> ? */ >>> -void svc_sock_destroy(struct svc_xprt *xprt) >>> +static void svc_bc_sock_free(struct svc_xprt *xprt) >>> ?{ >>> ? ? ? if (xprt) >>> ? ? ? ? ? ? ? kfree(container_of(xprt, struct svc_sock, sk_xprt)); >>> ?} >>> -EXPORT_SYMBOL_GPL(svc_sock_destroy); >>> +#endif /* CONFIG_NFS_V4_1 */ >>> -- >>> 1.6.6 >>> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at ?http://vger.kernel.org/majordomo-info.html >> >